1. Field of the Invention
The present invention relates to a magnetic tape recorder-player, and more particularly, to a tape guide angle controlling apparatus for a magnetic tape recorder-player which maintains a desired tape running angle during either forward running or reverse running of the tape so as to improve tape running in both cases.
2. Description of Related Art
As shown in FIG. 1, a conventional tape running device in a magnetic tape recorder-player includes a supply guide unit 400 provided on the path along which a tape T is transferred from a supply reel 1 onto a head drum 4, and a roller guide unit 500 provided on the path along which the tape T is transported from the head drum 4 onto a takeup reel 9.
After sequentially passing a first post P0, a tension post 2, a second post P1, a full-erase head 3, a roller P2 and a first slant post SP of the supply guide unit 400, the tape T is supplied to the head drum 4.
The roller guide unit 500 includes a second slant post TP, another roller P3, and audio/control head 5, a third post P4, a capstan 6, a pinch roller 7 and a tape guide 8.
When the tape T is run forward, the tape T runs along the guide units 400 and 500 in the above-described sequence. When run in reverse, the tape T runs in the reverse sequence.
The roller P2, the first slant post SP, the roller P3 and the second slant post TP each enable the tape T to be drawn out, so that the tape T can be wrapped onto the headdrum 4.
In the tape running cycle of the conventional magnetic tape recorder described above, the tape guide 8 serves to guide the tape T during both the forward and reverse tape running modes.
The structure for driving the tape guide 8 in the roller guide unit 500 will now be described.
Referring to FIG. 2, a pivot shaft 11 is mounted on a main base plate 10. A roller arm 12 is rotatably mounted at a hub end thereof on the pivot shaft 11. The tape guide 8 is vertically mounted on the distal end of the roller arm 12. A projection 12' is formed beneath the roller arm 12.
When the tape T is in a forward running mode, the tape guide 8 guides the tape T transferred past the capstan 6 thereto to be wound on the supply reel 9. In the reverse running mode, the tape guide 8 serves to regularly transfer, at a certain angle, the tape T from the takeup reel 9 to the capstan 6.
To operate the roller arm 12 having the tape guide 8 mounted at its one end, as shown in FIGS. 3A through 3C, there is provided a first connection gear 14 engaged to a gear 13' serving as a rotation shaft of a driving source 13. Also, there is provided a second connection gear 15 which is engaged to the first connection gear 14, and a cam gear 16 which is engaged to the second connection gear 15 for transmitting the driving force to the roller arm 12.
On a portion along the periphery of the cam gear 16 a cam arc projection 16' is formed for holding and driving the roller arm 12.
A lever recess 20 is formed at an outer edge surface of a function slide 17. Function slide 17 includes a rack gear 18 formed internally therein engaged to the third connection gear 19. Third connection gear 19 is also engaged to the cam gear 16. A brake protrusion 22 formed at one end portion of a supply reel brake lever 21 movably contacts the outer edge surface of the function slide 17 and follows along the outer edge surface of the function slide 17 to the lover recess 20, whereby an appropriate tension is applied to the tape T wound on the supply reel 9. Reference numeral 23 denotes a brake spring.
Among the operations of the conventional tape guide angle controlling apparatus in accordance with the conventional magnetic tape recorder-player, the forward running of the tape T will be first described.
The tape T supplied from the supply reel 1 is transferred to the head drum 4 by sequentially passing the first post P0, the tension post 2, the second post P1, the full-erase head 3, the roller P2 and the first slant post SP.
Then, the tape T moves via the roller guide unit 500 to the takeup reel 9. In the roller guide unit 500, the tape T sequentially passes the second slant post TP, the roller P3, the audio/control head 5, the third post P4, the capstan 6, the pinch roller 7 and the tape guide 8. At this time, the tape guide 8 moves according to the operation of the roller arm 12.
The cam gear 16 is driven by the operation of the second connection gear 15. Second connection gear 15 is engaged to the first connection gear 14, which is in turn engagedly powered by the shaft gear 13' extended from the driving source 13. With the rotation of the cam gear 16, a cam arc tip 16", formed along the periphery of the cam arc projection 16', pushes the arm projection 12' on the roller arm 12 so that the roller arm 12 is rotated clockwise, whereby the roller arm 12 as shown in FIG. 3A moves to the location thereof shown in FIG. 3B.
The third connection gear 19, which is engaged with the cam gear 16 and also with the rack gear 18 in the function slide 17, drives the function slide 17 from the position shown in FIG. 3A to the right.
To control the tape guide angle in the conventional magnetic tape recorder-player, when the tape T is run forward, the brake protrusion 22 provided at the end of the takeup reel brake lever 21 does not reach the lever recess 20, so the takeup reel 9 can rotate freely because it is not contacted by the takeup reel brake lever 21.
When the takeup reel 9 is not contacted by the takeup reel brake lever 21, the tape guide 8 at the end of the roller arm 12 guides the tape T from between the capstan 6 and the pinch roller 7 so as to be regularly wound onto the takeup reel 9. Meanwhile, when run in reverse, the tape T released from the takeup reel 9 and past the tape guide 8 is guided in the reverse direction compared to the forward running mode.
In the reverse running of the tape T, the tape guide 8 maintains the tape T released from the takeup reel 9 at a certain angle and guides the tape T to the capstan 6. The operation of the tape guide 8 will be described hereunder.
First, when the cam gear 16 and the cam arc projection 16' thereon are driven by the driving source 13, the cam arc projection 16' contacts the arm projection 12' on the roller arm 12 as shown in FIG. 2. Then, the arm projection 12' on the roller arm 12 contacts the cam arc tip 16"' of the cam arc projection 16'.
The third connection gear 19 engaged to the cam gear 16 is operated so as to move the function slide 17 to the right as shown in FIG. 3C.
When the function slide 17 moves to the right, the brake protrusion 22 at the end of the takeup reel brake lever 21 becomes positioned in the lever recess 20. Therefore, the other end of the takeup reel brake lever 21 contacts the periphery of the takeup reel 9, thereby controlling the rotation rate of the takeup reel 9.
The control of the speed of takeup reel 9 adds an appropriate initial tension to the tape T being unwound from the takeup reel 9.
Meanwhile, during forward running, the tape guide 8 maintains an appropriate tension on the tape T while enabling the tape T to be regularly wound onto the takeup reel 9. At this time, to properly guide the tape T from capstan 6, the tape guide 8 should be perpendicular to the main base plate 10. When running in reverse, the tape T having an appropriate tension thereon corresponding to the braking of the takeup reel brake lever 21 is supplied to the tape guide 8.
However, in the tape guide angle controlling apparatus in the conventional magnetic tape recorder-player, when running in reverse, so that the supply reel 1 receives the tape T, because of the long tape running path between the supply reel 1 and the capstan 6 for transporting the tape T, the tape running state becomes weakened when passing over the head drum 4, the first slant post SP and the second slant post TP, because of the long tape running path between the supply reel 1 and the capstan 6 for transporting the tape T. Therefore, the tape T contacted to the third post P4 and the audio/control head 5 may experience fluctuation perpendicularly to the tape running direction.
Therefore, the conventional tape guide angle controlling apparatus has disadvantages in that when the position of tape T fluctuates when running in reverse mode, the tape T can be damaged. Also, when the tape mode changes back to a forward running, the positional fluctuation of tape T causes delays in audio signal reproduction by the audio/control head 5 because head 5 cannot accurately reproduce signals from the tape.